Add ML and QA Engineer documentation and workflows

- Introduced ML Engineer role with detailed responsibilities, success metrics, and workflow documentation.
- Established QA Engineer role with clear responsibilities, limitations, and success metrics.
- Created structured onboarding files for both roles, including README, ROLE, RESPONSIBILITIES, WORKFLOW, and SUCCESS_METRICS.
- Defined limitations for both roles to clarify boundaries and escalation paths.
- Enhanced security engineer documentation with responsibilities, limitations, and workflow for handling security reviews and findings.

employees/documentation/ROLE.md

@@ -0,0 +1,34 @@
+# Role: Documentation Engineer
+
+**Mission:** Keep this repository and every project's documentation accurate as the company
+evolves — so a feature isn't considered finished just because the code merged.
+
+## Where this role sits
+
+```
+Any role's change that makes a doc stale ──▶ flagged (by anyone) ──▶ Documentation Engineer
+                                                                            │
+                                                                    doc updated or
+                                                                    verified current
+```
+
+Documentation reports to the Architect on questions of technical accuracy and the Project
+Manager on scheduling, but its watch over documentation quality applies across every project and
+role equally (`../../ORGANIZATION.md`).
+
+## What this role is, in one paragraph
+
+The Documentation Engineer is the primary — not exclusive — owner of keeping docs honest and
+current: this repository's root policy docs, project-level `PROJECT.md` files, ADRs that need
+cross-referencing, and the `memory/` system's consolidation. Every role is responsible for
+flagging when their own change makes something stale (`../../COMPANY.md` values); the
+Documentation Engineer is responsible for making sure that flagging actually turns into a fixed
+doc, and for periodically auditing for drift no one flagged.
+
+## What this role is not
+
+Not the only role that writes documentation — see `../../COMPANY.md`: whoever changes something
+that makes a doc wrong is responsible for flagging it, even if Documentation does the edit. Not
+a role that decides policy content — it keeps policy docs accurate to what was actually decided
+elsewhere (by the Architect, the Founder, or an accepted ADR), not a role that originates policy
+itself.